Yesterday, I told you about Yo, a ridiculous new messaging app which lets people exchange two-character “Yo” messages. Some like Stephen Colbert have eviscerated Yo for being utterly useless and plain dumb while others point out the fact that it’s received more than $1 million in VC-backed funding as a proof that the mobile messaging space is booming with innovation.

Be that as it may, turns out the controversial software poses something of a security risk as a pair of college students have found a vulnerability allowing them to compromise any Yo user’s phone number, spam them with unsolicited messages and more.

Yo founder Or Arbel has confirmed that the app was “having security issues” and has promised to deliver a fix “in next few hours”…

We can get any Yo user’s phone number (I actually texted the founder, and he called me back). We can spoof Yo’s from any users, and we can spam any user with as many Yo.

We could also send any Yo user a push notification with any text we want (though we decided not to do that).

Arbel told the publication that they’re working on a fix and promised it will be delivered in the next few hours:

Some of the stuff has been fixed and some we are still working on. We are taking this very seriously.

Here’s a hacked Yo.

Screenshot via Instagram user ‘stephzibi’.

Another hack unrelated to the aforementioned breach has Yo sounding out a snap of ‘Rick Astley’s “Never Gonna Give You Up” instead of its normal “Yo!” sound, as evidenced by a Vine video below.

It floors me that Yo is currently #5 on the App Store’s Top Free list.

You know you’re onto something when your product has become the topic of late night talk shows.

“Now there’s a new app that has expanded the possibilities for communication by drastically reducing them,” said Stephen Colbert. “That’s right, ‘Yo.’ An app that’s already hugely popular with the world’s population of Sylvester Stallone.”

Here’s Colbert having a field day with Yo because it doesn’t let you type your friends anything besides “Yo”.

I love the following excerpt from Colbert’s show:

When I first learned about an app that boils down all your communication into two letters, I expressed myself in one: ‘Y?’.

But I joined the Yo movement when I read the company boasts it takes 11 taps to send the word ‘yo’ on a rival messaging service compared to just two on their app. That’s a nine-tap difference. Taps you could be spending with your children.

And here’s a nice Yo review on Google’s Play store.

Yo’s Arbel told Business Insider that the app, which only took eight hours to develop, attracted more than 200,000 new users just 48 hours after its launch.